/* A simple event-driven programming library. Originally I wrote this code
 * for the Jim's event-loop (Jim is a Tcl interpreter) but later translated
 * it in form of a library for easy reuse.
 *
 * Copyright (c) 2006-2010, Salvatore Sanfilippo <antirez at gmail dot com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdio.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <time.h>

#include "ae.h"
#include "zmalloc.h"

/* Include the best multiplexing layer supported by this system.
 * The following should be ordered by performances, descending. */
#ifdef HAVE_EPOLL
#include "ae_epoll.cc"
#else
#ifdef HAVE_KQUEUE
#include "ae_kqueue.cc"
#else
#include "ae_select.cc"
#endif
#endif

#ifdef __MACH__
#include <mach/clock.h>
#include <mach/mach.h>
#endif

#if defined(__linux__)
# if !defined(ARCH_HAS_CLOCK_MONOTONIC_RAW)
#  include <linux/version.h>
#  if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,28)
# define ARCH_HAS_CLOCK_MONOTONIC_RAW
#endif // LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
#endif // !defined(ARCH_HAS_EVENTFD)
#endif // defined(linux)

aeEventLoop *aeCreateEventLoop(int setsize)
{
	aeEventLoop *eventLoop;
	int i;

    if ((eventLoop = zmalloc(sizeof(*eventLoop))) == NULL) goto err;
    eventLoop->events = zmalloc(sizeof(aeFileEvent)*setsize);
    eventLoop->fired = zmalloc(sizeof(aeFiredEvent)*setsize);
    if (eventLoop->events == NULL || eventLoop->fired == NULL) goto err;
    eventLoop->setsize = setsize;
	eventLoop->timeEventHead = NULL;
	eventLoop->timeEventNextId = 0;
	eventLoop->stop = 0;
	eventLoop->maxfd = -1;
	eventLoop->beforesleep = NULL;
    if (aeApiCreate(eventLoop) == -1) goto err;

	/* Events with mask == AE_NONE are not set. So let's initialize the
	 * vector with it. */
    for (i = 0; i < setsize; i++)
		eventLoop->events[i].mask = AE_NONE;
	return eventLoop;
err:
    if (eventLoop) {
        zfree(eventLoop->events);
        zfree(eventLoop->fired);
        zfree(eventLoop);
    }
    return NULL;
}

void aeDeleteEventLoop(aeEventLoop *eventLoop)
{
	aeApiFree(eventLoop);
    zfree(eventLoop->events);
    zfree(eventLoop->fired);
	zfree(eventLoop);
}

void aeStop(aeEventLoop *eventLoop)
{
	eventLoop->stop = 1;
}

int aeCreateFileEvent(aeEventLoop *eventLoop, int fd, int mask,
        aeFileProc *proc, void *clientData)
{
    if (fd >= eventLoop->setsize) return AE_ERR;
    aeFileEvent *fe = &eventLoop->events[fd];

	if (aeApiAddEvent(eventLoop, fd, mask) == -1)
		return AE_ERR;
	fe->mask |= mask;
	if (mask & AE_READABLE)
		fe->rfileProc = proc;
	if (mask & AE_WRITABLE)
		fe->wfileProc = proc;
	fe->clientData = clientData;
	if (fd > eventLoop->maxfd)
		eventLoop->maxfd = fd;
	return AE_OK;
}

void aeDeleteFileEvent(aeEventLoop *eventLoop, int fd, int mask)
{
    if (fd >= eventLoop->setsize) return;
    aeFileEvent *fe = &eventLoop->events[fd];

	if (fe->mask == AE_NONE)
		return;
	fe->mask = fe->mask & (~mask);
	if (fd == eventLoop->maxfd && fe->mask == AE_NONE)
	{
		/* Update the max fd */
		int j;

		for (j = eventLoop->maxfd - 1; j >= 0; j--)
			if (eventLoop->events[j].mask != AE_NONE)
				break;
		eventLoop->maxfd = j;
	}
	aeApiDelEvent(eventLoop, fd, mask);
}

int aeGetFileEvents(aeEventLoop *eventLoop, int fd) {
    if (fd >= eventLoop->setsize) return 0;
    aeFileEvent *fe = &eventLoop->events[fd];

    return fe->mask;
}

static void aeGetTime(long *seconds, long *milliseconds)
{
//	struct timeval tv;
//	gettimeofday(&tv, NULL);
//	*seconds = tv.tv_sec;
//	*milliseconds = tv.tv_usec / 1000;

	struct timeval val;
	gettimeofday(&val, 0);
	*seconds = val.tv_sec;
	*milliseconds = (val.tv_usec / 1000);
}

static void aeAddMillisecondsToNow(long long milliseconds, long *sec, long *ms)
{
	long cur_sec, cur_ms, when_sec, when_ms;

	aeGetTime(&cur_sec, &cur_ms);
	when_sec = cur_sec + milliseconds / 1000;
	when_ms = cur_ms + milliseconds % 1000;
	if (when_ms >= 1000)
	{
		when_sec++;
		when_ms -= 1000;
	}
	*sec = when_sec;
	*ms = when_ms;
}

long long aeCreateTimeEvent(aeEventLoop *eventLoop, long long milliseconds,
        aeTimeProc *proc, void *clientData, aeEventFinalizerProc *finalizerProc)
{
	long long id = eventLoop->timeEventNextId++;
	aeTimeEvent *te;

	te = zmalloc(sizeof(*te));
	if (te == NULL)
		return AE_ERR;
	te->id = id;
	aeAddMillisecondsToNow(milliseconds, &te->when_sec, &te->when_ms);
	te->timeProc = proc;
	te->finalizerProc = finalizerProc;
	te->clientData = clientData;
	te->next = eventLoop->timeEventHead;
	eventLoop->timeEventHead = te;
	return id;
}

/**
 * Add by wangqiying
 */
int aeModifyTimeEvent(aeEventLoop *eventLoop, long long id,
        long long milliseconds)
{
	aeTimeEvent *te;
	te = eventLoop->timeEventHead;
	while (te)
	{
		if (te->id == id)
		{
			aeAddMillisecondsToNow(milliseconds, &te->when_sec, &te->when_ms);
			return AE_OK;
		}
		//prev = te;
		te = te->next;
	}
	return AE_ERR; /* NO event with the specified ID found */
}

int aeDeleteTimeEvent(aeEventLoop *eventLoop, long long id)
{
	aeTimeEvent *te, *prev = NULL;

	te = eventLoop->timeEventHead;
	while (te)
	{
		if (te->id == id)
		{
			if (prev == NULL)
				eventLoop->timeEventHead = te->next;
			else
				prev->next = te->next;
			if (te->finalizerProc)
				te->finalizerProc(eventLoop, te->clientData);
			zfree(te);
			return AE_OK;
		}
		prev = te;
		te = te->next;
	}
	return AE_ERR; /* NO event with the specified ID found */
}

/* Search the first timer to fire.
 * This operation is useful to know how many time the select can be
 * put in sleep without to delay any event.
 * If there are no timers NULL is returned.
 *
 * Note that's O(N) since time events are unsorted.
 * Possible optimizations (not needed by Redis so far, but...):
 * 1) Insert the event in order, so that the nearest is just the head.
 *    Much better but still insertion or deletion of timers is O(N).
 * 2) Use a skiplist to have this operation as O(1) and insertion as O(log(N)).
 */
static aeTimeEvent *aeSearchNearestTimer(aeEventLoop *eventLoop)
{
	aeTimeEvent *te = eventLoop->timeEventHead;
	aeTimeEvent *nearest = NULL;

	while (te)
	{
		if (!nearest || te->when_sec < nearest->when_sec || (te->when_sec
		        == nearest->when_sec && te->when_ms < nearest->when_ms))
			nearest = te;
		te = te->next;
	}
	return nearest;
}

/* Process time events */
static int processTimeEvents(aeEventLoop *eventLoop)
{
	int processed = 0;
	aeTimeEvent *te;
	long long maxId;

	te = eventLoop->timeEventHead;
	maxId = eventLoop->timeEventNextId - 1;
	while (te)
	{
		long now_sec, now_ms;
		long long id;

		if (te->id > maxId)
		{
			te = te->next;
			continue;
		}
		aeGetTime(&now_sec, &now_ms);
		if (now_sec > te->when_sec || (now_sec == te->when_sec && now_ms
		        >= te->when_ms))
		{
			int retval;

			id = te->id;
			retval = te->timeProc(eventLoop, id, te->clientData);
			processed++;
			/* After an event is processed our time event list may
			 * no longer be the same, so we restart from head.
			 * Still we make sure to don't process events registered
			 * by event handlers itself in order to don't loop forever.
			 * To do so we saved the max ID we want to handle.
			 *
			 * FUTURE OPTIMIZATIONS:
			 * Note that this is NOT great algorithmically. Redis uses
			 * a single time event so it's not a problem but the right
			 * way to do this is to add the new elements on head, and
			 * to flag deleted elements in a special way for later
			 * deletion (putting references to the nodes to delete into
			 * another linked list). */
			if (retval != AE_NOMORE)
			{
				aeAddMillisecondsToNow(retval, &te->when_sec, &te->when_ms);
			}
			else
			{
				aeDeleteTimeEvent(eventLoop, id);
			}
			te = eventLoop->timeEventHead;
		}
		else
		{
			te = te->next;
		}
	}
	return processed;
}

/* Process every pending time event, then every pending file event
 * (that may be registered by time event callbacks just processed).
 * Without special flags the function sleeps until some file event
 * fires, or when the next time event occurrs (if any).
 *
 * If flags is 0, the function does nothing and returns.
 * if flags has AE_ALL_EVENTS set, all the kind of events are processed.
 * if flags has AE_FILE_EVENTS set, file events are processed.
 * if flags has AE_TIME_EVENTS set, time events are processed.
 * if flags has AE_DONT_WAIT set the function returns ASAP until all
 * the events that's possible to process without to wait are processed.
 *
 * The function returns the number of events processed. */
int aeProcessEvents(aeEventLoop *eventLoop, int flags)
{
	int processed = 0, numevents;


	/* Nothing to do? return ASAP */
	if (!(flags & AE_TIME_EVENTS) && !(flags & AE_FILE_EVENTS))
		return 0;

	/* Note that we want call select() even if there are no
	 * file events to process as long as we want to process time
	 * events, in order to sleep until the next time event is ready
	 * to fire. */
	if (eventLoop->maxfd != -1 || ((flags & AE_TIME_EVENTS) && !(flags
	        & AE_DONT_WAIT)))
	{
		int j;
		aeTimeEvent *shortest = NULL;
		struct timeval tv, *tvp;

		if (flags & AE_TIME_EVENTS && !(flags & AE_DONT_WAIT))
			shortest = aeSearchNearestTimer(eventLoop);
		if (shortest)
		{
			long now_sec, now_ms;


			/* Calculate the time missing for the nearest
			 * timer to fire. */
			aeGetTime(&now_sec, &now_ms);
			tvp = &tv;
			tvp->tv_sec = shortest->when_sec - now_sec;
			if (shortest->when_ms < now_ms)
			{
				tvp->tv_usec = ((shortest->when_ms + 1000) - now_ms) * 1000;
				tvp->tv_sec--;
			}
			else
			{
				tvp->tv_usec = (shortest->when_ms - now_ms) * 1000;
			}
			if (tvp->tv_sec < 0)
				tvp->tv_sec = 0;
			if (tvp->tv_usec < 0)
				tvp->tv_usec = 0;
		}
		else
		{
			/* If we have to check for events but need to return
			 * ASAP because of AE_DONT_WAIT we need to se the timeout
			 * to zero */
			if (flags & AE_DONT_WAIT)
			{
				tv.tv_sec = tv.tv_usec = 0;
				tvp = &tv;
			}
			else
			{
				/* Otherwise we can block */
				tvp = NULL; /* wait forever */
			}
		}
		numevents = aeApiPoll(eventLoop, tvp);

		for (j = 0; j < numevents; j++)
		{
			aeFileEvent *fe = &eventLoop->events[eventLoop->fired[j].fd];
			int mask = eventLoop->fired[j].mask;
			int fd = eventLoop->fired[j].fd;
			int rfired = 0;


			/* note the fe->mask & mask & ... code: maybe an already processed
			 * event removed an element that fired and we still didn't
			 * processed, so we check if the event is still valid. */
			if (fe->mask & mask & AE_READABLE)
			{
				rfired = 1;
				fe->rfileProc(eventLoop, fd, fe->clientData, mask);
			}
			if (fe->mask & mask & AE_WRITABLE)
			{
				if (!rfired || fe->wfileProc != fe->rfileProc)
					fe->wfileProc(eventLoop, fd, fe->clientData, mask);
			}
			processed++;
		}
	}
	/* Check time events */
	if (flags & AE_TIME_EVENTS)
		processed += processTimeEvents(eventLoop);

	return processed; /* return the number of processed file/time events */
}

/* Wait for millseconds until the given file descriptor becomes
 * writable/readable/exception */
int aeWait(int fd, int mask, long long milliseconds)
{
	struct timeval tv;
	fd_set rfds, wfds, efds;
	int retmask = 0, retval;

	tv.tv_sec = milliseconds / 1000;
	tv.tv_usec = (milliseconds % 1000) * 1000;
	FD_ZERO(&rfds);
	FD_ZERO(&wfds);
	FD_ZERO(&efds);

	if (mask & AE_READABLE)
		FD_SET(fd, &rfds);
	if (mask & AE_WRITABLE)
		FD_SET(fd, &wfds);
	if ((retval = select(fd + 1, &rfds, &wfds, &efds, &tv)) > 0)
	{
		if (FD_ISSET(fd, &rfds))
			retmask |= AE_READABLE;
		if (FD_ISSET(fd, &wfds))
			retmask |= AE_WRITABLE;
		return retmask;
	}
	else
	{
		return retval;
	}
}

void aeMain(aeEventLoop *eventLoop)
{
	eventLoop->stop = 0;
	while (!eventLoop->stop)
	{
		if (eventLoop->beforesleep != NULL)
			eventLoop->beforesleep(eventLoop);
		aeProcessEvents(eventLoop, AE_ALL_EVENTS);
	}
}

char *aeGetApiName(void)
{
	return aeApiName();
}

void aeSetBeforeSleepProc(aeEventLoop *eventLoop,
        aeBeforeSleepProc *beforesleep)
{
	eventLoop->beforesleep = beforesleep;
}
